The SIG Sauer P250 air pistol uses a 12-gram CO2 cartridge. It features a semi-auto blowback design, a 16 round mag, manual safety, and fixed sights. The durable polymer frame with integral picatinny accessory rail and metal slide are built to last. This CO2 powered air pistol has been life tested for 15,000 shots! Specifications and Features: SIG Sauer P250 CO2 Air Pistol Semi Automatic Blowback Uses a 12-Gram CO2 Cartridge .177 Caliber (4.5mm) 16 Rounds Velocity 500 fps Loudness: (4)Medium-High Rifled Barrel Manual Safety Fixed Sights Integral Picatinny Accessory Rail Polymer Frame Metal Slide Black Life tested for 15,000 shots